Three patients with adolescent hepatomas and normal WBC counts, were found to have a novel glycoprotein causing extraordinary elevations of serum vitamin B12 (15-53 ng/ml; normal 0.2-1.0 ng/ml) and vitamin B12 unbound binding capacity (20-533 ng/ml; normal 1-2 ng/ml). Preliminary studies of ten other younger children (age 6 months to 4 years) with hepatoma suggested similar abnormalities, although in lesser amounts. The hepatoma serum B12 binding protein appeared to be tumor related since it increased in amount as the disease progressed and was present in large amounts in metastatic pleural effusion. The hepatoma B12 binding protein was isolated from the pleural fluid of one of these patients using affinity chromatography. This glycoprotein was found to contain increased sialic acid residues but similar amino acid composition, and molecular weight as compared to normal B12 binding protein isolated from human saliva and milk. To further evaluate these findings we propose to (1) isolate additional hepatoma serum B12 binding proteins using affinity chromatography; (2) produce antiserum to purified hepatoma serum B12 binding protein to use for immunologic identification of small amounts of the B12 binding protein; (3) study the size, content and characteristics of purified hepatoma serum B12 binding protein; (4) develop a cell line from human hepatoma capable of producing the hepatoma serum B12 binding protein; (5) locate where in the cell the hepatoma serum B12 binding protein is found; (6) study the purified binder by isoelectric focusing techniques. (7) establish the frequency of this novel B12 binding protein in hepatoma and other neoplasms; (8) examine the possibility that abnormal transferrins ceruloplasmins or alpha 1 anti-trypsins are also found in hepatoma serum; (9) establish if a tumor related enzyme or lack of enzyme can modify the sialic composition of serum transport proteins; and (10) measure the catabolism and cellular clearance of labeled, isolated hepatoma B12 binding protein and the role of sialic acid in this process.